UMTS

Javier Sanchez Mamadou Thioune

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UMTS

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UMTS

Javier Sanchez Mamadou Thioune

Part of this book adapted from the 2nd edition of UMTS published in France by Herms Science/Lavoisier in 2004 First Published in Great Britain and the United States in 2007 by ISTE Ltd Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd ISTE USA 6 Fitzroy Square 4308 Patrice Road London W1T 5DX Newport Beach, CA 92663 UK USA

www.iste.co.uk ISTE Ltd, 2007 LAVOISER, 2004 The rights of Javier Sanchez and Mamadou Thioune to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Cataloging-in-Publication Data Sanchez, Javier. UMTS/Javier Sanchez, Mamadou Thioune. p. cm. ISBN-13: 978-1-905209-71-2 ISBN-10: 1-905209-71-1 1. Universal Mobile Telecommunications System. I. Thioune, Mamadou. II. Title. III. Title: Universal mobile telecommunications system. TK5103.4883.S36 2006 621.3845'6--dc22

2006035535

British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 10: 1-905209-71-1 ISBN 13: 978-1-905209-71-2

Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire.

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Chapter 1. Evolution of Cellular Mobile Systems . . . . . . . . . . . . . . . . 1

1.1. Multiple-access techniques used in mobile telephony . . . . . . . . . . . 2 1.1.1. Frequency division duplex (FDD) and time division duplex (TDD). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.2. Frequency division multiple access (FDMA) . . . . . . . . . . . . . 3 1.1.3. Time division multiple access (TDMA). . . . . . . . . . . . . . . . . 3 1.1.4. Code division multiple access (CDMA) . . . . . . . . . . . . . . . . 3 1.1.5. Space division multiple access (SDMA) . . . . . . . . . . . . . . . . 5 1.1.6. Orthogonal frequency division multiplexing (OFDM) . . . . . . . . 6

1.2. Evolution from 1G to 2.5G. . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.1. From 1G to 2G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.2. Enhancements to 2G radio technologies: 2.5G. . . . . . . . . . . . . 8

1.3. 3G systems in IMT-2000 framework. . . . . . . . . . . . . . . . . . . . . 11 1.3.1. IMT-2000 radio interfaces . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.2. Core network approaches in 3G systems . . . . . . . . . . . . . . . . 18

1.4. Standardization process in 3G systems. . . . . . . . . . . . . . . . . . . . 19 1.5. Worldwide spectrum allocation for IMT-2000 systems . . . . . . . . . . 20

1.5.1. WARC-92 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.5.2. WARC-2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 2. Network Evolution from GSM to UMTS . . . . . . . . . . . . . . 25

2.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2. UMTS definition and history . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.3. Overall description of a UMTS network architecture . . . . . . . . . . . 27 2.4. Network architecture evolution from GSM to UMTS . . . . . . . . . . . 28

2.4.1. GSM network architecture of Phases 1 and 2 . . . . . . . . . . . . . 28 2.4.2. GSM network architecture of Phase 2+ . . . . . . . . . . . . . . . . . 29

vi UMTS

2.4.3. Architecture of UMTS networks: evolutionary revolution of GSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5. Bearer services offered by UMTS networks . . . . . . . . . . . . . . . . 32 2.6. UMTS protocol architecture based on stratum concept. . . . . . . . . 33

2.6.1. Access stratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2.6.2. Non-access stratum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Chapter 3. Services in UMTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.2. UMTS mobile terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.2.1. UE functional description . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.2.2. UE maximum output power. . . . . . . . . . . . . . . . . . . . . . . . 41 3.2.3. Dual-mode GSM/UMTS terminals . . . . . . . . . . . . . . . . . . . 42 3.2.4. UE radio access capability . . . . . . . . . . . . . . . . . . . . . . . . 43

3.3. Services offered by UMTS networks. . . . . . . . . . . . . . . . . . . . . 44 3.3.1. Standard UMTS telecommunication services . . . . . . . . . . . . . 44 3.3.2. UMTS bearer services . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.3.3. Teleservices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.3.4. Supplementary services . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.3.5. Operator specific services: service capabilities . . . . . . . . . . . . 54 3.3.6. The virtual home environment . . . . . . . . . . . . . . . . . . . . . . 55

3.4. Traffic classes of UMTS bearer services . . . . . . . . . . . . . . . . . . 56 3.4.1. Conversational services . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.4.2. Streaming services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.4.3. Interactive services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.4.4. Background services . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

3.5. Service continuity across GSM and UMTS networks . . . . . . . . . . . 58 Chapter 4. UMTS Core Network. . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.2. UMTS core network architecture . . . . . . . . . . . . . . . . . . . . . . . 61

4.2.1. Main features of UMTS core network based on Release 99 . . . . . 62 4.2.2. Circuit-switched and packet-switched domains . . . . . . . . . . . . 63

4.3. Network elements and protocols of the CS and PS domains . . . . . . . 65 4.3.1. Network elements of the CS domain . . . . . . . . . . . . . . . . . . 65 4.3.2. Protocol architecture in the CS domain . . . . . . . . . . . . . . . . . 66 4.3.3. Network elements of the PS domain. . . . . . . . . . . . . . . . . . . 71 4.3.4. Protocol architecture in the PS domain . . . . . . . . . . . . . . . . . 72 4.3.5. Integrated UMTS core network . . . . . . . . . . . . . . . . . . . . . 80

4.4. Network elements not included in UMTS reference architecture . . . . 81 4.5. Interoperability between UMTS and GSM core networks . . . . . . . . 82

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Chapter 5. Spread Spectrum and WCDMA . . . . . . . . . . . . . . . . . . . . 85 5.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.2. Spread spectrum principles . . . . . . . . . . . . . . . . . . . . . . . . . . 85

5.2.1. Processing gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 5.2.2. Advantages of spread spectrum . . . . . . . . . . . . . . . . . . . . . 87

5.3. Direct sequence CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 5.4. Multiple access based on spread spectrum . . . . . . . . . . . . . . . . . 90 5.5. Maximum capacity of CDMA. . . . . . . . . . . . . . . . . . . . . . . . . 91

5.5.1. Effect of background noise and interference . . . . . . . . . . . . . . 92 5.5.2. Antenna sectorization . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 5.5.3. Voice activity detection . . . . . . . . . . . . . . . . . . . . . . . . . . 93

5.6. Spreading code sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 5.6.1. Orthogonal code sequences . . . . . . . . . . . . . . . . . . . . . . . . 95 5.6.2. Pseudo-noise code sequences: Gold codes . . . . . . . . . . . . . . . 96 5.6.3. Spreading sequences used in UTRA. . . . . . . . . . . . . . . . . . . 98

5.7. Principles of wideband code division multiple access . . . . . . . . . . . 99 5.7.1. Effects of the propagation channel. . . . . . . . . . . . . . . . . . . . 100 5.7.2. Techniques used in WCDMA for propagation impairment mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Chapter 6. UTRAN Access Network . . . . . . . . . . . . . . . . . . . . . . . . 113

6.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 6.2. UTRAN architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

6.2.1. The radio network sub-system (RNS) . . . . . . . . . . . . . . . . . . 115 6.2.2. Handling of the mobility in the UTRAN . . . . . . . . . . . . . . . . 119 6.2.3. Summary of functions provided by the UTRAN . . . . . . . . . . . 120

6.3. General model of protocols used in UTRAN interfaces. . . . . . . . . . 121 6.3.1. Horizontal layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 6.3.2. Vertical planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 6.3.3. Control plane of the transport network . . . . . . . . . . . . . . . . . 124

6.4. Use of ATM in the UTRAN network transport layer . . . . . . . . . . . 125 6.4.1. ATM cell format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 6.4.2. ATM and virtual connections. . . . . . . . . . . . . . . . . . . . . . . 126 6.4.3. ATM reference model . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

6.5. Protocols in the Iu interface . . . . . . . . . . . . . . . . . . . . . . . . . . 128 6.5.1. Protocol architecture in Iu-CS and Iu-PS interfaces. . . . . . . . . . 128 6.5.2. RANAP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

6.6. Protocols in internal UTRAN interfaces . . . . . . . . . . . . . . . . . . . 134 6.6.1. Iur interface (RNC-RNC) . . . . . . . . . . . . . . . . . . . . . . . . . 134 6.6.2. Iub interface (RNC-Node B) . . . . . . . . . . . . . . . . . . . . . . . 137

6.7. Data exchange in the UTRAN: example of call establishment. . . . . . 139 6.8. Summary of the UTRAN protocol stack. . . . . . . . . . . . . . . . . . . 141

viii UMTS

Chapter 7. UTRA Radio Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . 145 7.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 7.2. Channel typology and description . . . . . . . . . . . . . . . . . . . . . . 146

7.2.1. Logical channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 7.2.2. Transport channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 7.2.3. Physical channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

7.3. Physical layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 7.3.1. Physical layer functions . . . . . . . . . . . . . . . . . . . . . . . . . . 153 7.3.2. Mapping of transport channels onto physical channels. . . . . . . . 154

7.4. MAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 7.4.1. Main functions of MAC . . . . . . . . . . . . . . . . . . . . . . . . . . 157 7.4.2. Mapping of logical channels onto transport channels. . . . . . . . . 157 7.4.3. MAC PDU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

7.5. RLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 7.5.1. Main functions of RLC . . . . . . . . . . . . . . . . . . . . . . . . . . 161 7.5.2. RLC PDU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 7.5.3. RLC transmission and reception model . . . . . . . . . . . . . . . . . 165

7.6. PDCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 7.7. BMC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 7.8. RRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

7.8.1. Handling of the RRC connection. . . . . . . . . . . . . . . . . . . . . 170 7.8.2. Handling of RRC service states . . . . . . . . . . . . . . . . . . . . . 171 7.8.3. System information broadcast . . . . . . . . . . . . . . . . . . . . . . 173 7.8.4. Handling of the paging. . . . . . . . . . . . . . . . . . . . . . . . . . . 175 7.8.5. Cell selection and reselection . . . . . . . . . . . . . . . . . . . . . . . 176 7.8.6. UTRAN mobility handling . . . . . . . . . . . . . . . . . . . . . . . . 176 7.8.7. Radio bearer management. . . . . . . . . . . . . . . . . . . . . . . . . 179 7.8.8. Measurement control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 7.8.9. Ciphering and integrity . . . . . . . . . . . . . . . . . . . . . . . . . . 183 7.8.10. Outer loop power control . . . . . . . . . . . . . . . . . . . . . . . . 185 7.8.11. Protocol layers termination in the UTRAN . . . . . . . . . . . . . . 185

Chapter 8. Call and Mobility Management . . . . . . . . . . . . . . . . . . . . 187

8.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 8.2. PLMN selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

8.2.1. Automatic PLMN selection mode . . . . . . . . . . . . . . . . . . . . 190 8.2.2. Manual PLMN selection mode . . . . . . . . . . . . . . . . . . . . . . 190 8.2.3. PLMN reselection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 8.2.4. Forbidden PLMNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

8.3. Principle of mobility management in UMTS . . . . . . . . . . . . . . . . 192 8.3.1. Location areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 8.3.2. Service states in the core network and the UTRAN. . . . . . . . . . 195

Table of Contents ix

8.4. Network access control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 8.4.1. Allocation of temporary identities . . . . . . . . . . . . . . . . . . . . 195 8.4.2. UE identification procedure. . . . . . . . . . . . . . . . . . . . . . . . 196 8.4.3. Ciphering and integrity protection activation . . . . . . . . . . . . . 197 8.4.4. Authentication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

8.5. Network registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.5.1. IMSI attach procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.5.2. GPRS attach procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 202

8.6. UE location updating procedures . . . . . . . . . . . . . . . . . . . . . . . 205 8.6.1. Location updating procedure . . . . . . . . . . . . . . . . . . . . . . . 205 8.6.2. Routing area updating procedure. . . . . . . . . . . . . . . . . . . . . 207 8.6.3. SRNS relocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 8.6.4. Detach procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

8.7. Call establishment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 8.7.1. Circuit call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 8.7.2. Packet call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

8.8. Intersystem change and handover between GSM and UMTS networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

8.8.1. Intersystem handover from UMTS to GSM during a CS connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 8.8.2. Intersystem handover from GSM to UMTS during a CS connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 8.8.3. Intersystem change from UMTS to GPRS during a PS session . . . 223 8.8.4. Intersystem change from GPRS to UMTS during a PS session . . . 223

Chapter 9. UTRA/FDD Transmission Chain . . . . . . . . . . . . . . . . . . . 227

9.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 9.2. Operations applied to transport channels . . . . . . . . . . . . . . . . . . 228

9.2.1. Multiplexing and channel coding in the uplink . . . . . . . . . . . . 228 9.2.2. Multiplexing and channel coding in the downlink . . . . . . . . . . 236

9.3. Operations applied to physical channels . . . . . . . . . . . . . . . . . . . 238 9.3.1. Characteristics of physical channels in UTRA/FDD . . . . . . . . . 238 9.3.2. Channelization codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 9.3.3. Scrambling codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 9.3.4. UTRA/WCDMA transmitter . . . . . . . . . . . . . . . . . . . . . . . 244

9.4. Spreading and modulation of dedicated physical channels . . . . . . . . 248 9.4.1. Uplink dedicated channels . . . . . . . . . . . . . . . . . . . . . . . . 248 9.4.2. Downlink dedicated channel . . . . . . . . . . . . . . . . . . . . . . . 255 9.4.3. Time difference between uplink and downlink DPCHs . . . . . . . 260

9.5. Spreading and modulation of common physical channels . . . . . . . . 261 9.5.1. The Physical Random Access Channel (PRACH). . . . . . . . . . . 261 9.5.2. The Physical Common Packet Channel (PCPCH). . . . . . . . . . . 262 9.5.3. The Physical Downlink Shared Channel (PDSCH) . . . . . . . . . . 263

x UMTS

9.5.4. The Synchronization Channel (SCH) . . . . . . . . . . . . . . . . . . 264 9.5.5. The Common Pilot Channel (CPICH). . . . . . . . . . . . . . . . . . 265 9.5.6. The Primary Common Control Physical Channel (P-CCPCH) . . . 266 9.5.7. The Secondary Common Control Physical Channel (S-CCPCH). . 267 9.5.8. The Paging Indicator Channel (PICH) . . . . . . . . . . . . . . . . . 268 9.5.9. The Acquisition Indicator Channel (AICH) . . . . . . . . . . . . . . 268 9.5.10. Other downlink physical channels associated with the PCPCH . . 269

Chapter 10. UTRA/FDD Physical Layer Procedures . . . . . . . . . . . . . . 271

10.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 10.2. The UE receptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 10.3. Synchronization procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 273

10.3.1. First step: slot synchronization . . . . . . . . . . . . . . . . . . . . . 274 10.3.2. Second step: frame synchronization and code-group identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 10.3.3. Third step: primary scrambling code identification . . . . . . . . . 276 10.3.4. Fourth step: system frame synchronization . . . . . . . . . . . . . . 276

10.4. Random access transmission with the RACH . . . . . . . . . . . . . . . 277 10.5. Random access transmission with the CPCH . . . . . . . . . . . . . . . 279 10.6. Paging decoding procedure. . . . . . . . . . . . . . . . . . . . . . . . . . 280 10.7. Power control procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

10.7.1. Open loop power control. . . . . . . . . . . . . . . . . . . . . . . . . 282 10.7.2. Inner loop and outer loop power control . . . . . . . . . . . . . . . 283

10.8. Transmit diversity procedures . . . . . . . . . . . . . . . . . . . . . . . . 286 10.8.1. Time Switched Transmit Diversity (TSTD) . . . . . . . . . . . . . 287 10.8.2. Space Time block coding Transmit Diversity (STTD) . . . . . . . 288 10.8.3. Closed loop transmit diversity . . . . . . . . . . . . . . . . . . . . . 289

Chapter 11. Measurements and Procedures of the UE in RRC Modes . . . 291

11.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 11.2. Measurements performed by the physical layer. . . . . . . . . . . . . . 291

11.2.1. Measurement model for physical layer . . . . . . . . . . . . . . . . 292 11.2.2. Types of UE measurements . . . . . . . . . . . . . . . . . . . . . . . 293

11.3. Cell selection process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 11.3.1. PLMN search and selection . . . . . . . . . . . . . . . . . . . . . . . 295 11.3.2. Phases in the cell selection process. . . . . . . . . . . . . . . . . . . 296 11.3.3. S cell selection criterion . . . . . . . . . . . . . . . . . . . . . . . . 298

11.4. Cell reselection process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 11.4.1. Types of cell reselection . . . . . . . . . . . . . . . . . . . . . . . . . 300 11.4.2. Measurement rules for cell reselection. . . . . . . . . . . . . . . . . 301 11.4.3. R ranking criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 11.4.4. Phases in the cell reselection process . . . . . . . . . . . . . . . . . 302

11.5. Handover procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

Table of Contents xi

11.5.1. Phases in a handover procedure. . . . . . . . . . . . . . . . . . . . . 304 11.5.2. Intrafrequency handover . . . . . . . . . . . . . . . . . . . . . . . . . 305 11.5.3. Interfrequency handover . . . . . . . . . . . . . . . . . . . . . . . . . 310 11.5.4. Intersystem UMTS-GSM handover . . . . . . . . . . . . . . . . . . 312

11.6. Measurements in idle and connected RRC modes . . . . . . . . . . . . 312 11.6.1. Measurements in RRC idle, CELL_PCH and URA_PCH states . . . . 312 11.6.2. Measurements in CELL_FACH state . . . . . . . . . . . . . . . . . . . 313 11.6.3. Measurements in the CELL_DCH state: the compressed mode . . . 315

Chapter 12. UTRA/TDD Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

12.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321 12.2. Technical aspects of UTRA/TDD . . . . . . . . . . . . . . . . . . . . . . 321

12.2.1. Advantages of UTRA/TDD . . . . . . . . . . . . . . . . . . . . . . . 322 12.2.2. Drawbacks of UTRA/TDD . . . . . . . . . . . . . . . . . . . . . . . 324

12.3. Transport and physical channels in UTRA/TDD . . . . . . . . . . . . . 325 12.3.1. Physical channel structure . . . . . . . . . . . . . . . . . . . . . . . . 326 12.3.2. Dedicated Physical Data Channels . . . . . . . . . . . . . . . . . . . 328 12.3.3. Common physical channels . . . . . . . . . . . . . . . . . . . . . . . 329

12.4. Service multiplexing and channel coding . . . . . . . . . . . . . . . . . 334 12.4.1. Examples of UTRA/TDD user bit rates . . . . . . . . . . . . . . . . 335

12.5. Physical layer procedures in UTRA/TDD . . . . . . . . . . . . . . . . . 336 12.5.1. Power control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 12.5.2. Downlink transmit diversity . . . . . . . . . . . . . . . . . . . . . . . 338 12.5.3. Timing advance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339 12.5.4. Dynamic channel allocation . . . . . . . . . . . . . . . . . . . . . . . 339 12.5.5. Handover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340

12.6. UTRA/TDD receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 Chapter 13. UMTS Network Evolution. . . . . . . . . . . . . . . . . . . . . . . 343

13.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343 13.2. UMTS core network based on Release 4 . . . . . . . . . . . . . . . . . . 345 13.3. UMTS core network based on Release 5 . . . . . . . . . . . . . . . . . . 347 13.4. Multimedia Broadcast/Multicast Service (MBMS). . . . . . . . . . . . 349

13.4.1. Network aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 13.4.2. MBMS operation modes . . . . . . . . . . . . . . . . . . . . . . . . . 350 13.4.3. MBMS future evolution . . . . . . . . . . . . . . . . . . . . . . . . . 351

13.5. UMTS-WLAN interworking . . . . . . . . . . . . . . . . . . . . . . . . . 352 13.5.1. UMTS-WLAN interworking scenarios . . . . . . . . . . . . . . . . 352 13.5.2. Network and UE aspects . . . . . . . . . . . . . . . . . . . . . . . . . 354

13.6. UMTS evolution beyond Release 7 . . . . . . . . . . . . . . . . . . . . . 355 13.6.1. HSDPA/HSUPA enhancements . . . . . . . . . . . . . . . . . . . . 356 13.6.2. System Architecture Evolution . . . . . . . . . . . . . . . . . . . . . 356 13.6.3. Long Term Evolution (LTE) . . . . . . . . . . . . . . . . . . . . . . 357

xii UMTS

Chapter 14. Principles of HSDPA . . . . . . . . . . . . . . . . . . . . . . . . . . 359 14.1. HSDPA physical layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

14.1.1. HS-DSCH transport channel . . . . . . . . . . . . . . . . . . . . . . 361 14.1.2. Mapping of HS-DSCH onto HS-PDSCH physical channels . . . . 362 14.1.3. Physical channels associated with the HS-DSCH . . . . . . . . . . 363 14.1.4. Timing relationship between the HS-PDSCH and associated channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

14.2. Adaptive modulation and coding . . . . . . . . . . . . . . . . . . . . . . 366 14.3. Hybrid Automatic Repeat Request (H-ARQ) . . . . . . . . . . . . . . . 367 14.4. H-ARQ process example . . . . . . . . . . . . . . . . . . . . . . . . . . . 369 14.5. Fast scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 14.6. New architecture requirements for supporting HSDPA . . . . . . . . . 371

14.6.1. Impact on Node B: high-speed MAC entity . . . . . . . . . . . . . 371 14.6.2. Impact on the UE: HSDPA terminal capabilities . . . . . . . . . . 372

14.7. Future enhancements for HSDPA . . . . . . . . . . . . . . . . . . . . . . 373 14.7.1. Enhanced UTRA/FDD uplink. . . . . . . . . . . . . . . . . . . . . . 373 14.7.2. Multiple Input Multiple Output antenna processing . . . . . . . . . 374

Appendix 1. AMR Codec in UMTS . . . . . . . . . . . . . . . . . . . . . . . . . 375

A1.1. AMR frame structure and operating modes . . . . . . . . . . . . . . . . 376 A1.2. Dynamic AMR mode adaptation . . . . . . . . . . . . . . . . . . . . . . 378 A1.3. Resource allocation for an AMR speech connection . . . . . . . . . . 380 A1.4. AMR wideband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380

Appendix 2. Questions and Answers . . . . . . . . . . . . . . . . . . . . . . . . 383

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

Preface

During the first decade of this millennium, more than 100 billion will be invested in third generation (3G) Universal Mobile Telecommunications System (UMTS) in Europe. This fact represents an amazing challenge from both a technical and commercial perspective. In the evolution path of GSM/GPRS standards, the UMTS proposes enhanced and new services including high-speed Internet access, video-telephony, and multimedia applications such as streaming.

Based on the latest updates of 3GPP specifications, this book investigates the differences of a GSM/GPRS network compared with a UMTS network as well as the technical aspects that ensure their interoperability. Students, professors and engineers will find in this book a clear and concise picture of key ideas behind the complexity of UMTS networks. This can also be used as a starter before exploring in more depth the labyrinth of 3GPP specifications which remain, however, the main technical reference.

Written by experts in their respective fields, this book gives detailed description of the elements in the UMTS network architecture: the User Equipment (UE), the UMTS Radio Access Network (UTRAN) and the core network. Completely new protocols based on the needs of the new Wideband Code Division Multiple Access (WCDMA) air interface are given particular attention by considering both Frequency- and Time-Division Duplex modes. Later on, the book further introduces the key features of existing topics in Releases 5, 6 and 7 such as High Speed Downlink/Uplink Packet Access (HSDPA/HSUPA), IP Multimedia Subsystem (IMS), Long Term Evolution (LTE), WLAN interconnection and Multicast/ Broadcast Multimedia Services (MBMS).

We would like to offer our heartfelt thanks to all our work colleagues for their helpful comments.

xiv UMTS

Some of the figures and tables reproduced in this book are the result of technical specifications defined by the 3GPP partnership (http://www.3gpp.org/3G_Specs/ 3G_Specs.htm). The specifications are by nature not fixed and are susceptible to modifications during their transposition in regional standardization organizations which make up the membership of the 3GPP partnership. Because of this, and as a result of the translation and/or adaptation of these points by the authors, these organizations cannot be considered responsible for the figures and tables reproduced in this book.

Chapter 1

Evolution of Cellular Mobile Systems

The purpose of this chapter is to describe the milestones in the evolution of cellular mobile systems. Particular attention is paid to the third generation (3G) systems to which the UMTS belong.

The performance of mobile cellular systems is often discussed with respect to the radio access technology they support, thus neglecting other important aspects. However, a cellular mobile communication system is much more than a simple radio access method, as illustrated in Figure 1.1. The mobile terminal is the vector enabling a user to access the mobile services he subscribed to throughout the radio channel. The core network is in charge of handling mobile-terminated and mobile-originated calls within the mobile network and enables communication with external networks, both fixed and mobile. Billing and roaming functions are also located in the core network. The transfer of users data from the terminal to the core network is the role of the radio access network. Implementing appropriate functions gives to the core network and to the terminal the impression of communicating in a wired link. One or several radio access technologies are implemented in both the radio access network and the mobile terminal to enable wireless radio communication.

Radio access network Core network

Mobile communications networkRadio access technology

Fixed & mobile networks (PSTN, ISDN, Internet)Radio access network Core network

Mobile communications networkRadio access technology

Fixed & mobile networks (PSTN, ISDN, Internet)

Figure 1.1. Basic components of a mobile communications network

2 UMTS

1.1. Multiple-access techniques used in mobile telephony

Surveying the different multiple-access techniques is equivalent to describing the key milestones in the evolution of modern mobile communication systems. In the past, not all users of the radio spectrum recognized the need for the efficient use of the spectrum. The spectrum auctions for UMTS licenses have emphasized the fact that the radio spectrum is a valuable resource. Thus, the major challenge of multiple-access techniques is to provide efficient allocation of such a spectrum to the largest number of subscribers, while offering higher data rates, increased service quality and coverage.

1.1.1. Frequency division duplex (FDD) and time division duplex (TDD)

Conventional mobile communication systems use duplexing techniques to separate uplink and downlink transmissions between the terminal and the base station. Frequency division duplex (FDD) and time division duplex (TDD) are among the transmission modes which are the most commonly employed. The main difference between the two modes, as shown in Figure 1.2, is that FDD uses two separate carrier bands for continuous duplex transmission, whereas in TDD duplex transmission is carried in alternate time slots in the same frequency channel. In order to minimize mutual interference in FDD systems, a guard frequency is required between the uplink and downlink allocated frequencies (usually 5% of the carrier frequency). On the other hand, a guard period in TDD systems is required in order to reduce mutual interference between the links. Its length is decided from the longest round-trip delay in a cellular system (in the order of 20-50 s).

DLf1

ULf2

freq

u enc

y

time

Guard frequency

(a) FDD mode

f1

freq

u enc

y

time

Guard period

(b) TDD mode

UL: UplinkDL: Downlink

UL DL DL DL DL UL

Base station

Base station

Mobile terminal

Mobile terminal

DLf1

ULf2

freq

u enc

y

time

Guard frequency

(a) FDD mode

f1

freq

u enc

y

time

Guard period

(b) TDD mode

UL: UplinkDL: Downlink

UL DL DL DL DL UL

Base station

Base station

Mobile terminal

Mobile terminal

Figure 1.2. Duplexing modes used in modern mobile communications systems

Evolution of Cellular Mobile Systems 3

1.1.2. Frequency division multiple access (FDMA)

FDMA is the access technology used for first generation analog mobile systems such as the American standard AMPS (Advanced Mobile Phone Service). Within an FDMA system, each subscriber is assigned a specific frequency channel as illustrated in Figure 1.3a. No one else in the same cell or in a neighboring cell can use the frequency channel while it is allocated to a user when an FDMA terminal establishes a call, it reserves the frequency channel for the entire duration of the call. This fact makes FDMA systems the least efficient cellular systems since each physical channel can only be used by one user at a time. Far from having disappeared, the FDMA principle is part most of modern digital mobile communication systems where it is used as a complement to other radio multiplexing schemes.

1.1.3. Time division multiple access (TDMA)

GSM, TDMA/136 and PCS are second generation mobile standards based on TDMA. The key idea behind TDMA relies on the fact that a user is assigned a particular time slot in a frequency carrier and can only send or receive information in those particular times (see Figure 1.3b). When all available time slots in a given frequency are used, the next user must be assigned a time slot on another frequency. Information flow is not continuous for any user, but rather is sent and received in bursts. The important factor to be considered while designing is that these time slices are so small that the human ear does not perceive the time being divided. In GSM up to 8 users may in theory share the same 200 kHz frequency band almost simultaneously, whereas in IS-136 different users can be allocated to 3 time slots within a 30 kHz frequency channel. The capacity of TDMA is about 3 to 6 times as much as that of FDMA [RAP 96].

1.1.4. Code division multiple access (CDMA)

In a CDMA system, unique digital codes, rather than separate radio frequencies, are used to differentiate users (see Figure 1.3c). The codes are shared by the terminal and the base station. All users access the entire spectrum allocation all of the time, that is, every user uses the entire block of allocated spectrum space to carry his/her message. CDMA technology is used in 2G IS-95 (cdmaOne) mobile communication systems and is also part of UMTS and cdma2000 3G standards.

4 UMTS

a) FDMA

utilisateur 2

user 3

base station

f1

fr eq u

e nc y

time

f2

f3

user 2

user 1

frequency

time

spec

tral d

ensit

y

f1

f1

f2f3

f1

call 1 call 2 call 3

b) FDMA/TDMA

f2

utilisateur 2

user 3

base station

t1 ti me

frequency

t2

t3

user 2

user 1

f1frequency

time

spec

tral d

ensit

y

f1f2

f3 t1

t2

t3

call 1call 2

call 3

call 4

call 7

call 5call 6

call 8call 9

c) FDMA/CDMA

base station

frequency

frequency

spec

tral d

ensit

y

c1

c2

c3

c4call 4

call 3

call 2

call 1c1

c2

c3

c4call 8

call 7

call 6

call 5c1

c2

c3

c4call 12

call 11

call 10

call 9

f1 f2 f3

timeuser 4

c1 c ode

c2

c3

utilisateur 2

user 3

user 2

user 1

c4

a) FDMA

utilisateur 2

user 3

base station

f1

fr eq u

e nc y

time

f2

f3

user 2

user 1

frequency

time

spec

tral d

ensit

y

f1

f1

f1

f2f3

f1

call 1 call 2 call 3

b) FDMA/TDMA

f2

utilisateur 2

user 3

base station

t1 ti me

frequency

t2

t3

user 2

user 1

f1frequency

time

spec

tral d

ensit

y

f1f2

f3 t1

t2

t3

call 1call 2

call 3

call 4

call 7

call 5call 6

call 8call 9

c) FDMA/CDMA

base station

frequency

frequency

spec

tral d

ensit

y

c1

c2

c3

c4call 4

call 3

call 2

call 1c1

c2

c3

c4call 8

call 7

call 6

call 5c1

c2

c3

c4call 12

call 11

call 10

call 9

f1 f2 f3

timeuser 4

c1 c od e

c2

c3

utilisateur 2

user 3

user 2

user 1

c4

Figure 1.3. FDMA, TDMA and CDMA multiplex access principle

Evolution of Cellular Mobile Systems 5

A very popular example used to stress the differences between FDMA, TDMA and CDMA is as follows.

Imagine a large room (frequency spectrum) intended to accommodate many pairs of people. Due to dividing walls, individual offices can be created within the room. They are then allocated to each pair of people so that their conversation can be isolated from noise generated by the other parties. Each office is like a single frequency/channel (principle of FDMA). No one else could use the office until the conversation was complete, whether or not the different pairs were actually talking. A better usage of each office can be achieved by accommodating multiple pairs of people within the same room. For this to work, each party shall respect a rule that is to keep silent while one pair is talking (principle of TDMA). The important factor to be considered is that these silence periods shall be small enough that the human ear cannot perceive the time slicing.

In the analogy with CDMA technology, all the offices are eliminated to create open-spaces instead, so that conversation can be carried out at any time. The rule is now for all pairs to hold their conversations in a different language the brains of contiguous pairs of people being able to naturally filter interference from the other pairs. The languages are analog to the codes assigned by the CDMA system. In theory, it should be possible to accommodate in the large room as much pairs as permitted by the cubic-volume of each person and provided that the number of available languages is enough. Unfortunately, even if the parties speak in different languages, a sudden raise of the voice volume of one couple may disturb the conversations of all the neighboring pairs. This problem may be overcome by implementing an automatic mechanism to control the voice volume of each party. In a CDMA system, this is actually a power control scheme whose performance is of paramount importance for the system to operate properly. However, despite such mechanism, adding the contribution of all the voices, no matter how low their level is, may produce an overall background noise in the room that makes it too difficult to hold a clear conversation. In such a case, some couples may be required to get out from the room or just to remain silent.

1.1.5. Space division multiple access (SDMA)

SDMA technique is based on deriving and exploiting information on the spatial position of mobile terminals. The radiation pattern of the base station is adapted in both uplink and downlink directions to each different user in order to obtain, as illustrated in Figure 1.4, the highest gain in the direction of the mobile user. At the same time, radiation which is zero shall be positioned in the directions of interfering mobile terminals, the ultimate goal being the overall enhancement of capacity and coverage within the mobile system [RHE 96]. SDMA approach can be integrated

6 UMTS

with different multiple access techniques (FDMA, TDMA, CDMA) and therefore it can be optionally used in all modern mobile communications systems.

user 1

user 2

user N

f1

f1

f1

base station

interferer

user 1

user 2

user N

f1

f1

f1

base station

interferer

Figure 1.4. Space division multiple access (SDMA) principle

1.1.6. Orthogonal frequency division multiplexing (OFDM)

OFDM is a special case of multi-carrier modulation. The main idea is to split a data stream into N parallel streams of reduced data rate and transmit each of them on a separate sub-carrier. High spectral efficiency is achieved in OFDM since a large number of sub-carriers where overlapping spectra is used. OFDM can be combined with FDMA, TDMA and CDMA methods in order to obtain the access schemes referred to as MC-FDMA, MC-TDMA and MC-CDMA, respectively (see Figure 1.5).

OFDM has been adopted in the terrestrial digital video broadcasting (DVB-T) standard and in the digital audio broadcasting (DAB) standard followed by the wireless local area network standards IEEE 802.11a/g, IEEE 802.16, BRAN, HIPERLAN/2 and HIPERMAN. Although not used in current 2G/3G mobile radio systems, the successful deployment of the OFDM technique has encouraged several studies intended to design new broadband air interfaces for 4G mobile systems (see Chapter 13).

Evolution of Cellular Mobile Systems 7

Sub-

carr

ier

a) MC-FDMAtime

OFDM symbols

user 1user 2

user 2user 1

Sub-

carr

ier

a) MC-FDMAtime

OFDM symbols

user 1user 2

user 2user 1

Sub-

carr

ier

b) MC-TDMAtime

OFDM symbols

user

1us

er 2

user

1

user

2

Sub-

carr

ier

b) MC-TDMAtime

OFDM symbols

user

1us

er 2

user

1

user

2

Sub-

carr

ier

c) MC-CDMAtime

OFDM symbols

user 1 and user 2

Sub-

carr

ier

c) MC-CDMAtime

OFDM symbols

user 1 and user 2

Figure 1.5. Examples of multiple access for two users based on the OFDM principle

8 UMTS

1.2. Evolution from 1G to 2.5G

Rather than a revolution, third-generation (3G) systems are an evolution from second-generation (2G) digital systems.

1.2.1. From 1G to 2G

1G phones were analog, used for voice calls only, and their signals were transmitted by the method of frequency modulation (FM). AMPS was the first 1G system to start operating in the USA (in July 1978). It was based on the FDMA technique and FDD. In Europe, the situation was every man for himself and almost each country developed a standard in its own: Radiocom 2000 in France, NMT 900 in Nordic countries, TACS in England, NETZ in Germany, etc. International roaming was at that time more of a utopia.

2G mobile telephone networks were the logical next stage in the development of cellular mobile systems after 1G, and they introduced for the first time a mobile phone system that used purely digital technology. At the end of the last century, 2G mobile phones become a mass consumer product due to the amazing progress in semiconductors reducing the size and cost of electronic components. Also, aggressive deregulation of telecommunications policies enabled the development of several operators within a same country, thus leading to attractive subscription offers. Being digital, 2G systems introduced new services besides traditional voice transmission, such as short messaging service (SMS) and fax. They also enabled the access to digital fixed networks like Internet and ISDN.

One of the successful 2G digital systems is GSM, a European mobile phone standard based on the TDMA technique. Around 70% of mobile phone subscribers in the world have adopted GSM nowadays. In the USA, a different form of TDMA is used in the system known as TDMA/136 (formerly IS-136 or D-AMPS) and there is another US system called IS-95 (cdmaOne), based on the CDMA approach. Finally, the Personal Digital Communications (PDC) standard is the Japanese contribution to 2G, which also relies on the TDMA principle. Table 1.1 shows key radio characteristics of 2G mobile cellular systems.

1.2.2. Enhancements to 2G radio technologies: 2.5G

By the late 1990s the market was ready for new mobile communication technologies to evolve from 2G and created pressure for enhanced data delivery and telephony services, global roaming, Internet access, email, and even video. Unfortunately, standards for 3G systems were in the process of being developed. A

Evolution of Cellular Mobile Systems 9

more immediate solution to meet these demands was needed, thus leading to the so-called 2.5G.

Standard TDMA/136 (D-AMPS) IS-95

(cdmaOne) GSM PDC

Origin USA USA Europe Japan

Commerciallaunch 1992 1995 1992 1993

Main operation

band (Mhz)

824-849 (UL) 869-894 (DL)

1,850-1,910 (UL) 1,930-1,990 (DL)

824-849 (UL) 869-894 (DL)

1,850-1,910 (UL)1,930-1,990 (DL)

824-849 (UL) 869-894 (DL) 880-915 (UL) 925-960 (DL)

1,710-1,785 (UL)1,805-1,880 (DL)1,850-1,910 (UL)1,930-1,990 (DL)

810-826 (UL) 940-956 (DL)

1,429-1,453 (UL) 1,477-1,501 (DL)

Access method FDMA/TDMA FDMA/CDMA FDMA/TDMA FDMA/TDMA

Duplexing FDD FDD FDD FDD

Channel bandwidth 30 kHz 1,250 kHz 200 kHz 25 kHz

Modulation /4 DQPSK QPSK/O-QPSK GMSK /4 DQPSK

Table 1.1. Comparison of radio specifications for 2G cellular mobile systems

As shown in Figure 1.6, three technologies have most often been proposed to upgrade GSM in the context of 2.5G: High-Speed Circuit Switched Data (HSCSD), General Packet Radio Service (GPRS) and Enhanced Data Rates for Global Evolution (EDGE). HSCSD enables transfer rates of up to 57.6 Kbps by allocating more than one time slot per user. GPRS enables the efficient use of the air interface by accommodating flexible user rates for packet oriented transfer using time slot

10 UMTS

assignment on demand (rather than via permanent occupation as in GSM and HSCSD). The result is an improved data rate of up to (theoretical) 171.2 Kbps (8 21.4 Kbps), versus the 9.6 Kbps rate of standard GSM networks. EDGE offers advanced modulation (8-QPSK in addition to GMSK) to achieve higher data rates (in the theoretical order of 384 Kbps). By applying EDGE to GPRS and EDGE to HSCSD, the hybrid techniques EGPRS and ECSD are obtained, respectively. While the role of ECSD in todays cellular market is marginal, EGPRS has been adopted by several GSM operators to make cost-effective the investments on GPRS and as a complement to UMTS network coverage.

IS-95B brings about improvements for handover algorithms in multi-carrier environments to the first version of the cdmaOne standard (IS-95A). Although IS-95B is based on CDMA, its logic for improvement is very similar to that of GPRS: rather than time slots given to the user as in GPRS, in IS-95B channels can still be aggregated to allow higher data rates of up to 115 Kbps bundling up to eight 14.4 or 9.6 Kbps data channels.

IS-136HS outdoor384 kbps (GPRS/EDGE)

EGPRS

UMTS

UTRA/TDD2 Mbps

IS-136HS indoor2 Mbps

2G 2.5G 3G

cdmaOne A< 14.4 kbps

PDC/PDC-P< 30 kbps

GSM < 14.4 kbps

IS-136< 14.4 kbps

IS-136+64 kbps

GSM/GPRS171.2 kbps

UTRA/FDD2 Mbps

cdma2000 phase 2(cdma2000 3X-MC)

2 Mbps

cdma2000 phase 1(cdma2000 1X-MC)

307 kbps

cdmaOne B115 kbps

HSDPA10 Mbps

HSUPA5.5 Mbps

GSM/HSCSD57 kbps

3.5G

cdma2000 1XEV-DV3.1 Mbps

cdma2000 1XEV-DO(HDR) 2.4 Mbps

IS-136HS outdoor384 kbps (GPRS/EDGE)

EGPRS

UMTS

UTRA/TDD2 Mbps

IS-136HS indoor2 Mbps

2G 2.5G 3G

cdmaOne A< 14.4 kbps

PDC/PDC-P< 30 kbps

GSM < 14.4 kbps

IS-136< 14.4 kbps

IS-136+64 kbps

GSM/GPRS171.2 kbps

UTRA/FDD2 Mbps

cdma2000 phase 2(cdma2000 3X-MC)

2 Mbps

cdma2000 phase 1(cdma2000 1X-MC)

307 kbps

cdmaOne B115 kbps

HSDPA10 Mbps

HSUPA5.5 Mbps

HSDPA10 Mbps

HSUPA5.5 Mbps

GSM/HSCSD57 kbps

3.5G

cdma2000 1XEV-DV3.1 Mbps

cdma2000 1XEV-DO(HDR) 2.4 Mbps

Figure 1.6. Migration of 2G standards towards 3G. Some data rates are purely theoretical and they may be different depending on the

hypothesis considered for their calculation

Evolution of Cellular Mobile Systems 11

TDMA/136 is also being enhanced to provide better voice capabilities, capacity, coverage, quality and data rates. In its evolution to 3G, an intermediate phase is envisaged where the bitrate of 30 kHz radio carrier will be increased by means of high-level modulation and by the use of 6 time slots rather than 3 within a 40 ms frame. This enhanced version of TDMA/136 is designated by 136+. By applying GPRS technology, packet transmission data rates of up to 64 Kbps can be obtained.

In 2001, Japan was the first country to introduce a 3G system commercially known as FOMA (Freedom Of Mobile Multimedia Access). It was based on an early version of UMTS standard specifications. Unlike the GSM systems, which developed various ways to deal with demand for improved services, Japan had no 2.5G enhancement stage to bridge the gap between 2G and 3G, and so the move into the new standard was seen as a fast solution to their capacity problems in PDC networks. Nevertheless, the standard implemented a packet mode variant to PDC (P-PDC), which gives packet data rates of up to 28.8 Kbps.

After the USA that leaded the 1G of mobile cellular systems; after Europe that played the first role in 2G, Asia, and more precisely, Japan, China and Korea, are willing to be the key players in the newborn 3G.

1.3. 3G systems in IMT-2000 framework

It is wrong to believe that UMTS is the only 3G system around the world, although this was the original purpose of the ITU (International Telecommunications Union). This unique 3G system should be called FPLMTS (Future Public Land Mobile Telecommunications System). The name being unpronounceable, it was changed to IMT-2000 (IMT stands for international mobile telecommunications1). A problem arose when, in 1998, no less that ten terrestrial radio access technologies were submitted to the ITU by its members the regional standardization organisms. In the end, the term IMT-2000 generated not a single 3G standard but a family of standards, most of them associated to their numerous 2G predecessors. Note that IMT-2000 consists of both terrestrial component and satellite component radio interfaces. Only the analysis of its terrestrial radio interfaces is in the scope of this book.

1 The number 2000 was supposed to represent: the year 2000, when the ITU expected the system would become available; the data rates offering services around 2000 Kbps and the spectrum in the 2000 MHz region that the ITU hoped to make it available worldwide.

12 UMTS

The key features of 3G systems in the IMT-2000 framework are:

high data rates. Minimum 144 Kbps in high mobility environments (more than 120 km/h); 384 Kbps, in common mobility environments (less than 120 km/h) and 2 Mbps, achievable in stationary and low mobility environments (less than 10 km/h);

support for circuit-switched services (e.g. PSTN- and ISDN-based networks) as well as packet-switched services (e.g. IP-based networks);

capability for multimedia applications, involving services with different quality of services (bitrate, bit error rate, delay, etc.);

high voice quality; similar to that provided by wired-networks;

small terminal for worldwide use and with worldwide roaming capability;

compatibility of services within IMT-2000 and with the fixed networks;

interoperability with their 2G/2.5G predecessors.

Restraining the definition of a 3G system to radio data rates and mobility environments made the term 3G become rather vague. This can be understood by keeping in mind that at that time (around 1992) usage of Internet was limited to academic and technical circles. The definition was originally quite specifically defined, as any standard that provided mobile users with the performance of ISDN or better. It is one of the goals of this book to show all the technical innovations behind a 3G network such as UMTS in addition to the amazing feats performed by its radio access technology (UTRA).

1.3.1. IMT-2000 radio interfaces

The radio interfaces for the terrestrial component of IMT-2000 are shown in Table 1.2, whereas Table 1.3 lists their major technical parameters. Parameters of DECT technology were deliberately omitted since this is not a major player in the 3G networks arena today, but this may change in the future.

NOTE. besides the names given by IMT-2000, there is no global consensus on how to designate the 3G radio access technologies out of the ITU framework. For instance, UTRA/FDD and UTRA/TDD radio interfaces are often called WCDMA (Wideband-CDMA).

Evolution of Cellular Mobile Systems 13

3G radio access technology IMT-2000 designation

UTRA/FDD Universal terrestrial radio access

frequency division duplex IMT-2000 CDMA Direct Spread

UTRA/TDD UTRA time division duplex

TD-SCDMA (low chip rate UTRA/TDD)

Time division synchronous CDMA

IMT-2000 CDMA TDD

Cdma2000 IMT-2000 CDMA Multi-carrier

UWC-136 Universal wireless communications IMT-2000 CDMA Single-carrier

DECT Digital enhanced cordless

telecommunications IMT-2000 FDMA/TDMA

Table 1.2. Radio access technologies defined in the IMT-2000 framework. The terms Cdma2000, UWC-136 and DECT designate also a complete 3G mobile network. The term

multi-carrier given to cdma2000 does not mean that the OFDM technique is implemented

1.3.1.1. IMT-2000 radio access technologies used by UMTS networks

A UMTS network may use either UTRA/FDD, UTRA/TDD, TD-SCDMA or DECT radio access technologies.

IMT-2000 CDMA Direct Spread: UTRA/FDD

This radio interface is called universal terrestrial radio access (UTRA) FDD or wideband CDMA (WCDMA). UTRA/FDD employs CDMA as radio access technology. Based on direct sequence CDMA approach, the chip rate is 3.84 Mcps and operates in paired frequency bands with a 5 MHz bandwidth carrier in UL and the same in DL (see Figure 1.7a). It should be stressed that current UMTS systems deployed in Europe and in Japan are based exclusively on UTRA/FDD technology.

14 UMTS

IMT-2000 CDMA TDD: UTRA/TDD

This radio interface is called UTRA/TDD and comprises two variants, called 1.28 Mcps TDD (TD-SCDMA) and 3.84 Mcps TDD. Chinese standardization authorities originally proposed TD-SCDMA as an alternative to European UTRA/TDD. A harmonization process was then carried out and TD-SCDMA is now part of UTRA/TDD specifications and it is referred to as the UTRA/TDD low-chip rate option [TS 25.843, R4].

5 MHz ( 2)

a) UTRA/FDD

5 MHz ( 2)

a) UTRA/FDD

b) Cdma2000

1.25 MHz

1X 1X 1X

1.25 MHz 1.25 MHz

GBGB

5 MHz ( 2)

b) Cdma2000

1.25 MHz

1X 1X 1X

1.25 MHz 1.25 MHz

GBGB

5 MHz ( 2)

5 MHz

c) UTRA/TDD (3.84 Mcps variant)

5 MHz

c) UTRA/TDD (3.84 Mcps variant)

d) TS-SCDMA (1.28 Mcps variant)

1.6 MHz 1.6 MHz 1.6 MHz5 MHz

d) TS-SCDMA (1.28 Mcps variant)

1.6 MHz 1.6 MHz 1.6 MHz5 MHz

Figure 1.7. Spectrum usage for IMT-2000 technologies based on CDMA (GB: guard band)